Thread cutting device



Jan. 10, 1967 s. KECK 3,296,837

THREAD CUTTING DEVICE Filed Dec, 16, 1964 5 Sheets-Sheet l abs 6a Invenfor:

Sly/fill d e c Jan. 10, 1967 s. KECK 3,296,837

THREAD CUTTING DEVICE Filed D80. 16, 1964 5 SheetsSheet 12 Inventor:

Jan. 10, 1967 s. KECK 3,296,837

THREAD CUTTING DEVICE Filed Dec. 16, v 1964 5 heets-Sheet 5 Inventor.-

S/yfiv'cd/7E c 4 United States Patent Office 3,296,837 THREAD CUTTING DEVICE Siegfried Keck, Stetten, near Hechingen, Hohenzoiiern, Germany, assignor to Maschinenfahrik Carl Mei-z K.G., Hechingen, Hohenzollern, Germany Filed Dec. 16, 1964, Ser. No. 418,832 Claims priority, application Germany, Dec. 20, 1963, M 59,329 7 Ciaims. (Cl. 66-140) The present invention relates to a thread-cutting device of a knitting machine. For purposes of cutting off reinforcing threads in that part of a stocking which is to be reinforced such as the sole or the high heel, and also for purposes of cutting off threads when a thread change is being effected, circular cutters have successfully been used which are located above the dial disc and rotate coaxially with the cylinder and at the speed of the machine. The drawback of such an arrangement, however, consists in that the cut-off end of the thread is far too long.

In an effort to avoid such long thread ends, in other words, to move the location where the cut-off takes place closer to the knitting surface of the knocking-over sinker, the following devices have been suggested. For instance, a system of shears with shear blades crossing each other or moving toward each other are from the outside at an incline with regard to the cylinder axis so moved between the dial disc and the knit article moving away from the dial that the location of the cut will be above the needle circle and the withdrawn needles. The drawback of this cutting device consists in that, due to a high cylinder speed and a great number of needles, the shear blades have to be moved at a very high speed mechanically, electromagnetically or pneumatically. This in turn causes considerable wear and, therefore, unsafety during the cutting-off operation, and in addition thereto causes annoying vibrations and noises.

According to another heretofore known method of cutting off the threads at the above mentioned location of the cut, electrically heated incandescent filaments are employed. The employment of this method will, in connection with some chemical fibers, produce, in particular, two drawbacks. First of all, at the thread ends burr-like incrustations form which endanger the fine knitting during the stripping operation by the yarn puller. Furthermore, at the filaments incrustations occur which cause disturbances harmful affecting the quality of the goods.

It is therefore, an object of the present invention to provide a thread cutting device which will overcome the above mentioned drawbacks.

It is another object of this invention to provide a thread-cutting device which will cut off threads of very short length only as for instance of a length of from 1 to 2 millimeters.

Still another object of this invention consists in the provision of a device as set forth above which is relatively simple in construction and operation.

These and other objects and advantages of the invention will appear more clearly in connection with the accompanying drawings, in which:

FIG. 1 illustrates a thread-cutting device according to the present invention showing the location of the cut to be effected between dial disc and the knitting being withdrawn.

FIG. 2 illustrates a rotatable cutting knife with a plurality of teeth, said cutting knife being arranged on a stationary counter knife having a cutting tooth.

FIG. 3 shows a rotating flat cutting knife with two cutting edges, which cutting knife is mounted on a stationary counter knife having a cutting tooth.

3,296,837 Patented Jan. 10, 1967 FIG. 4 illustrates a thread-cutting device according to the invention for cutting the threads between the dial disc and the knit article and shows the device in a location above the needle circle and above the needles withdrawn for purposes of knitting off.

FIG. 5 represents an embodiment of the thread-cutting device according to the invention with separate drive by electric motor or air turbine.

FIGS. 6 and 7 respectively illustrate in working position and out of working position a device according to the invention in which, when a needle break occurs, the cutting teeth and cutting knives at the cutting station are protected against damage.

The present invention is characterized primarily in that a rotatable cutting knife is provided with at least one tooth and located eccentrically with regard to the cylinder axis, or a rotatable flat knife with at least one blade is pressed against a counter knife with at least one tooth and with a greater diameter adapted to protect the rotating knife against non-withdrawn needles. As a result thereof, there will be formed a cutting station which is always in readiness for a cutting operation and which is located inside the needle circle for the reinforcing threads or change ends guided thereto. This cutting station is introduced outside at an incline from the outside to the cylinder axis so deeply between the dial disc and the knit article moving away from the dial above the needles which are withdrawn for a knitting off-operation, that the threads can be cut off with extremely short ends.

In view of the high speed of the cutting knife which rotates noiselessly and in a vibration-free manner on the large surface of the stationary counter knife provided with at least one cutting tooth, there will be obtained a self-sharpening which greatly aids in maintaining an uninterrupted operation.

The necessary high speed of the rotating cutting knife may be effected separately mechanically, by an electric motor or by an air turbine. In conformity with the present invention, the drive of the rotating cutting knife with a great number of teeth is characterized in that a gear with line teeth which is fixedly connected to the dial disc and therefore rotates at the cylinder speed and concentrically with regard to the cylinder axis, rolls on a gear ring with similar teeth of the rotating cutting knife.

When the thread guiding device according to the invention is introduced between the dial disc and the knit article, it may, due to its location above the needles which are lowered for purposes of knitting off, be subjected to danger when a needle broken at the needle butt cannot be withdrawn. To meet such a situation, there is provided a protective and stopping device. This protective and stopping device is characterized in that the non-withdrawn needle moves against a lever which has a double function inasmuch as it places itslf in a protective manner in front of the cutting tooth of the counter knife so that the needle during its further course can spring against the larger circumference of the counter knife which protects the rotating cutting knife. Moreover, the entire thread cutting device is adapted when moving back above the needle circle to bring about the actuation of an electric circuit for stopping the machine.

Referring now to the drawing in detail, the arrangement shown therein comprises a rotating cutting knife 1 (FIG. 1) which may be designed in conformity with FIG. 2 or in conformity with the cutting knife la of FIG. 3, and rotates about a shaft 2 on a stationary counter knife 3. Knives 1 and 3 together form the cuttingoff station 22 for a thread 19 to be cut off. Counter knife 3 has a cutting tooth 4 (FIGS. 2 and 3) and its diameter is greater than the diameter of cutting knife 1 3 to such an extent that teeth of the rotatable cutting knife 1 (FIG. 2) or the two cutting edges 50 of cutting knife 1a (FIG. 3) will be protected against damage.

The thread cutting device is driven by teeth 1b pro vided on cutting knife 1 which mesh with the teeth 6a of a counter gear 6 (FIG. 1). Gear 6 is fixedly connected to a dial disc 7 and steps up the speed of the rotating cutting knife 1. Gear 6 is coaxially arranged with regard to the cylinder axis 23a and rotates at the same speed as cylinder 23. A disk 61) connected to the gear has its circumferential area provided with cutouts 69 which positively assure the feeding of threads 19 to be cut. A disc spring 20 arranged within a recess of cutting knife 1 or cutting knife 1a furnishes the pressure necessary for causing members 1 and 3, or 1a and 3 to sharpen each other.

The cutting device with teeth 5 and cutting edges 50 according to FIGS. 2 and 3 respectively would, for purposes of assuring extremely short thread ends, require a higher speed than could be obtained by means of the arrangement of FIG. 1. This higher speed is expediently obtained by the drive illustrated in FIG. 5 which is independent of the rotation of the cylinder and comprises an electric motor or air turbine 25.

FIG. 1 indicates how deep and to what extent the rotatable cutting knife 1 can be moved over needles 9, sinkers 24 and knitting 21 in order to permit cutting off of the threads with very short thread ends.

The thread cutting device is located at that portion of needle circle 8 (FIG. 4) where the needles 9 are being withdrawn for knitting off. FIG. 4 clearly illustrates needle circle 8 with needles 9 withdrawn for the knittingoff operation by means of cam members in a manner well known in the art. Cutting knife 1 has been moved inwardly above the needle circle 8 to such an extent that threads 19 which are fed by cutouts 60 of the disc 6b (shown only partially in FIG. 4) are conveyed to the cutting station 22 so that they can be cut off very closely.

If it should occur that a needle 9 cannot be withdrawn in view of a broken off butt, the needle will, in conformity with FIGS. 4 and 6 strike or abut against an arm 10- of a double-lever 11 pivotable about a shank 13. Arm 10 will thus be deflected into a protective position in front of cutting station 22 (FIGS. 4 and 7) which is formed by cutting tooth 4 (FIGS. 2 and 3) of counter knife 3 and teeth 5 or cutting edges 50 of rotating cutting knife 1, 1a, respectively. The non-withdrawn needle which is bent inwardly by the lever 10 will then spring back and slide along counter knife 3 without causing any damage. A counter lever 12 (FIGS. 6, 7) of a two-arm lever 11 will by means of a sliding bolt 14 cause a lever arm 15 to perform a tilting movement about a bolt 16 whereby the thread cutting device mounted on lever 15 will be tilted back from needle circle 8.

FIG. 6 illustrates the thread cutting device in its cutting position in which arm 10 of two-arm lever 11 is permitted to be located over needle circle 8 only to such an extent that the threads being introduced into the cutting station 22 will not be interfered with, while on the other hand a non-withdrawn needle 9 (as described in connection with FIG. 4) will take care of returning the thread cutting device to its rest position shown in FIG. 7 against the thrust of a spring 17. Lever 15 tiltable about a bolt 16 will abut against an electric contact 18 which in its turn will bring about stoppage of the machine.

When the thread cutting device is not needed, as for example, during a knitting operation which requires no cutting off of reinforcing threads and change ends, and therefore is not moved into effective position, in other words when the device is retained in its FIG. 7 position, contact 18 is turned back about a bolt 26 from its FIG. 7 position as indicated by the arrow A in FIG. 7. This tilting operation of contact 18 may be effected manually or in any other desired way.

It is, of course, to be understood that the present invention is, by no means, limited to the particular arrangements shown in the drawings, but also comprises any modifications within the scope of the appended claims. Thus, instead of the gear drive 1b, 6a, it is, of course, also possible to use any other drive, for instance a friction wheel drive. Furthermore, while stationary cutting knife 3 has been described as having one tooth 4 only, it may also be provided with a plurality of teeth.

The expression ripping disc as used in the specification and claims and has the meaning of the term dial as employed in knitting machines. In this connection and also for the understanding of other terms, machine parts and machine operation reference is made to the manuals Principles of Knitting, vols. 1 and 2 by William E. Shinn, published 1946 by Clark Publishing Company, 218 West Morehead Street, Charlotte 1, N.C.

What I claim is:

1. In combination with a knitting machine having a rotatable cylinder with independent needles arranged along a circle, and a dial disc; a cutting device for cutting off threads, especially reinforcing threads in the sole and heel area of stockings and for cutting off threads during the change of threads with round knitted stockings, said cutting device comprising: rotatable cutting means arranged eccentrically with regard to the axis of rotation of said cylinder, nonrotatable cutting means adjacent said rotatable cutting means and together therewith forming a cutting station for cutting off threads fed into the circle of needles, said nonrotatable cutting means protruding beyond said rotatable cutting means for protecting the latter against damage by non-withdrawn broken needles, said rotatable cutting means and said nonrotatable cutting means being inclined with regard to the axis of rotation of said cylinders so that the plane of said cutting station is located between said dial disc and the withdrawn needles whereby the thread to be cut off from a knitting being Withdrawn can be cut off very closely to the knitting, means supporting said cutting device for movement of said cutting station in said plane from an idle position outside the needle circle into cutting position where the cutting station intersects the needle circle in the region of the withdrawn needles, and means for initiating rotation of said rotatable cutting means in response to movement of said cutting station into cutting position.

2. An arrangement according to claim 1, in which said rotatable cutting means has at least one cutting tooth.

3. An arrangement according to claim 1, in which said rotatable cutting means has at least one fiat cutting blade.

4. In combination with a knitting machine having a rotatable cylinder with independent needles arranged along a circle, and a dial disc; a cutting device for cutting off threads, especially reinforcing threads in the sole and heel area of stockings and for cutting off threads during the change of threads with round knitted stockings, said cutting device comprising: rotatable cutting means arranged eccentrically with regard to the axis of rotation of said cylinder, nonrotatable cutting means adjacent said rotatable cutting means and together therewith forming a cutting station for cutting off threads fed into the circle of needles, spring means continuously and resiliently pressing said rotatable cutting means against said nonrotatable cutting means, said nonrotatable cutting means protruding beyond said rotatable cutting means for protecting the latter against damage by non-withdrawn broken needles, said rotatable cutting means and said nonrotatable cutting means being inclined with regard to the axis of rotation of said cylinder so that the plane of said cutting station is located between said dial disc and the withdrawn needles whereby the thread to be cut off from a knitting being withdrawn can be cut off very closely to the knitting, means supporting said cutting device for movement of said cutting station in said plane from an idle position outside the needle circle into cutting position where the cutting station intersects the needle circle in the region of the withdrawn needles, and means for initiating rotation of said rotatable cutting means in response to movement of said cutting station into cutting position.

5. In combination with a knitting machine having a rotatable cylinder with independent needles arranged along a circle, and a dial disc; a cutting device for cutting off threads, especially reinforcing threads in the sole and heel area of stockings and for cutting off threads during the change of threads with round knitted stockings, said cutting device comprising: rotatable cutting means arranged eccentrically with regard to the axis of rotation of said cylinder, nonrotatable cutting means adjacent said rotatable cutting mean and together therewith forming a cutting station for cutting off threads fed into the circle of needles, said nonrotatable cutting means protruding beyond said rotatable cutting means for protecting the latter against damage by non-withdrawn broken needles, said rotatable cutting means and said nonrotatable cutting means being inclined with regard to the axis of rotation of said cylinder so that the plane of said cutting station is located between said dial disc and the withdrawn needles whereby the thread to be cut oil from a knitting being withdrawn can be cut ofi very closely to the knitting, means supporting said cutting device for movement of said cutting station in said plane from an idle position outside the needle circle into cutting position where the cutting station intersects the needle circle in the region of the withdrawn needles, and means for initiating rotation of said rotatable cutting means in response to movement of said cutting station into cutting position, the last mentioned said means comprising drive means drivingly connecting said rotatable cutting means to said dial disc when said cutting station is in cutting position.

6. An arrangement according to claim 5, in which said drive means comprises an axial section of said rotating cutting means provided with first teeth, and an axial section of said dial disc provided with second teeth which mesh with said first teeth when said cutting device is moved to dispose said cutting station in cutting position, the ratio of said second teeth to said first teeth being such as to step up the speed of rotation of said rotatable cutting means relative to the rotation of said dial disc.

7. In combination with a knitting machine having a rotatable cylinder with independent needles arranged along a circle, and a dial disc; a cutting device for cutting 01? threads, especially reinforcing threads in the sole and heel area of stockings and for cutting off threads during the change of threads with round knitted stockings, said cutting device comprising: rotatable cutting means arranged eccentrically with regard to the axis of rotation of said cylinder, nonrotatable cutting means adjacent said rotatable cutting means and together therewith forming a cutting station for cutting off threads fed into the circle of needles, said nonrotatable cutting means protruding beyond said rotatable cutting means for protecting the latter against damage by non-withdrawn broken needles, said rotatable cutting means and said nonrotatable cutting means being inclined with regard to the axis of rotation of said cylinder so that the plane of said cutting station is located between said dial disc and the withdrawn needles whereby the thread to be cut oil from a knitting being withdrawn can be cut off very closely to the knitting, first lever means supporting said rotatable cutting means and said nonrotatable cutting means, first pivot means spaced from the axis of rotation of said rotatable cutting means and pivotally supporting said first lever means, spring means connected to said first lever means and continuously urging said rotatable and nonrotatable cutting means into a position in which said rotatable and nonrotatable cutting means extend into intersecting relation with the needle circle in the region of the withdrawn needles, second lever means having an arm extending into the path of needles in the needle circle approaching the region of withdrawn needles and being located ahead of said rotatable and nonrotatable cutting means when looking in the direction of rotation of said cylinder, second pivot means pivotally supporting said second lever means, connecting means operatively connecting said second and first lever means for tilting the latter about said first pivot means so as to move said cutting station into retracted position outside the range of the needle circle in response to said second lever means being tilted by a non-withdrawn needle along said circle of needles, and means operated by said first lever means when said first lever means is moved to retracted position and adapted for controlling a control circuit pertaining to said knitting machine for halting the knitting machine.

References Cited by the Examiner UNITED STATES PATENTS 2,713,254 7/1955 Minton 66--145 2,952,148 9/1960 Rather 66-140 3,055,199 9/1962 Stack 66-140 3,075,374 1/1963 St. Pierre 66145 3,100,976 8/1963 Billi et al. 66145 3,100,977 8/1963 Billi et al. 66-145 3,164,975 1/1965 Haberhauer 66140 3,197,977 8/1965 Stack 66140 3,206,948 9/1965 Bella et al. 66-l45 FOREIGN PATENTS 593,152 5/1959 Italy.

MERV IN STEIN, Primary Examiner.

R. PELDBAUM, Assistant Examiner. 

1. IN COMBINATION WITH A KNITTING MACHINE HAVING A ROTATABLE CYLINDER WITH INDEPENDENT NEEDLES ARRANGED ALONG A CIRCLE, AND A DIAL DISC; A CUTTING DEVICE FOR CUTTING OFF THREADS, ESPECIALLY REINFORCING THREADS IN THE SOLE AND HEEL AREA OF STOCKINGS AND FOR CUTTING OFF THREADS DURING THE CHANGE OF THREADS WITH ROUND KNITTED STOCKINGS, SAID CUTTING DEVICE COMPRISING: ROTATABLE CUTTING MEANS ARRANGED ECCENTRICALLY WITH REGARD TO THE AXIS OF ROTATION OF SAID CYLINDER, NONROTATABLE CUTTING MEANS ADJACENT SAID ROTATABLE CUTTING MEANS AND TOGETHER THEREWITH FORMING A CUTTING STATION FOR CUTTING OFF THREADS FED INTO THE CIRCLE OF NEEDLES, SAID NONROTATABLE CUTTING MEANS PROTRUDING BEYOND SAID ROTATABLE CUTTING MEANS FOR PROTECTING THE LATTER AGAINST DAMAGE BY NON-WITHDRAWN BROKEN NEEDLES, SAID ROTATABLE CUTTING MEANS AND SAID NONROTATABLE CUTTING MEANS BEING INCLINED WITH REGARD TO THE AXIS OF ROTATION OF SAID CYLINDERS SO THAT THE PLANE OF SAID CUTTING STATION IS LOCATED BETWEEN SAID DIAL DISC AND THE WITHDRAWN NEEDLES WHEREBY THE THREAD TO BE CUT OFF FROM A KNITTING BEING WITHDRAWN CAN BE CUT OFF VERY CLOSELY TO THE KNITTING, MEANS SUPPORTING SAID CUTTING DEVICE FOR MOVEMENT OF SAID CUTTING STATION IN SAID PLANE FROM AN IDLE POSITION OUTSIDE THE NEEDLE CIRCLE INTO CUTTING POSITION WHERE THE CUTTING STATION INTERSECTS THE NEEDLE CIRCLE IN THE REGION OF THE WITHDRAWN NEEDLES, AND MEANS FOR INITIATING ROTATION OF SAID ROTATABLE CUTTING MEANS IN RESPONSE TO MOVEMENT OF SAID CUTTING STATION INTO CUTTING POSITION. 